I. Technical Field
The present invention relates to integrated optics. More specifically, the present invention relates to optical modulators having wide linear dynamic range, useful in communication and computation systems employing optical frequency signals.
II. Background Art
Analog optical transmission has recently attracted renewed interest owing to the inherently low noise characteristics of fiber optics systems. With the advent of single mode systems, noise levels have been greatly reduced by eliminating modal noise within the fiber. Also, recent improvements in laser diodes have led to dramatically lower noise levels. With these advances in fiber optic technology, analog transmission becomes extremely attractive in applications where the desired signals at the terminal ends are analog, for example in commercial television. By eliminating the need for modulation conversion, the terminal equipment is greatly reduced in complexity and cost.
One remaining obstacle to widespread use of analog optical transmission is the intrinsic input current to output intensity nonlinearity of typical light emitting devices such as light emitting diodes or diode lasers. Distortion of the signal caused by nonlinearities can be a problem, particularly in multichannel systems, where a high degree of linearity is required to prevent interchannel cross-talk.
It is therefore desirable to have an optical modulator which has improved linearity over a wide dynamic range. Such an optical modulator would not rely on the input current to output intensity characteristics of the light generating device, but rather on the input to output characteristics of the modulator. Such a device having extremely linear response over a wide dynamic range would overcome the inherent limitations of previous optical modulation schemes.